The present invention relates to a magnetic disk apparatus having a plurality of magnetic heads.
In recent years, magnetic disk apparatuses have been widely used as memories for storing information in large quantities in computers such as personal computers, laptop computers, and notebook computers.
A magnetic disk apparatus of this type generally comprises a plurality of magnetic disks stacked inside, magnetic head assemblies having a plurality of magnetic heads for recording/reproducing information on/from the magnetic disks, a carriage for movably supporting the magnetic head assemblies with respect to the magnetic disks, and a voice coil motor for moving the magnetic heads to desired track positions on the magnetic disks by rotating the carriage.
The plurality of magnetic disks are fixed to the hub of a spindle motor and coaxially supported thereon at predetermined intervals in a stacked state. The magnetic disks are rotated at a predetermined speed by driving the spindle motor.
The magnetic head assemblies having the magnetic heads are provided in pairs for the respective magnetic disks. Each pair of assemblies are positioned to oppose the upper and lower surfaces of a corresponding magnetic disk. For example, in a magnetic disk apparatus having two magnetic disks, four magnetic head assemblies are arranged.
Each magnetic head assembly includes a slider, on which a magnetic head is formed, and a suspension for exerting a predetermined load on the magnetic head. The carriage includes a bearing assembly and a plurality of arms extending from the bearing assembly. The magnetic head assemblies are fixed to the corresponding arms.
In addition, the magnetic disk apparatus includes a circuit board for processing signals for the magnetic heads. This circuit board is electrically connected to the plurality of magnetic heads with the following arrangement.
A flexible printed circuit board (to be referred to as an FPC hereinafter) extends from the circuit board. The leading end portion of the FPC is fixed to the bearing assembly of the carriage. Many connection pads are formed on the leading end portion of the FPC.
For example, two lead lines extend from each magnetic head. These lead lines extend to a portion near the bearing assembly along the suspension and the arm. The distal ends of the lead lines are soldered to the connection pads of the FPC one by one.
As personal computers and the like equipped with magnetic disk apparatuses have recently become smaller in size and higher in performance, the demand for smaller magnetic disk apparatuses having larger capacities has grown year by year. In order to increase the capacity of a magnetic disk apparatus, the number of magnetic heads and the number of magnetic disks may be increased. Alternatively, high performance magnetic heads and high performance magnetic disks may be used.
On the other hand, as the demand for smaller magnetic disk apparatuses has grown, the packing density of the components of the apparatuses has increased, resulting in a deterioration in manufacturing efficiency. Problems are posed especially in association with the connection between the lead lines of magnetic heads and the circuit board.
That is, if the number of magnetic heads and the number of magnetic disks are increased to attain an increase in capacity, the number of head lead lines increases. Similarly, if high performance magnetic heads are used, since three or four head lead lines are required for each magnetic head, the total number of head lead lines increases. Accordingly, the number of connection pads of an FPC which extend from a circuit board must be increased.
Owing to the demands for a reduction in size, it is difficult to increase the area of the FPC. When the number of connection pads is to be increased, the area of each connection pad and the intervals between the pads must be decreased.
In the above conventional magnetic disk apparatus, however, each head lead line is soldered to a corresponding connection pad of the FPC which extends from the circuit board, and the operation of connecting each lead line to a corresponding connection pad becomes cumbersome with reductions in the area of each connection pad and the intervals between the pads. In addition, only experts can handle such a painstaking job. For this reason, the assembly efficiency for magnetic disk apparatuses deteriorates, and connection faults may be caused by errors such as connection point errors.